Grassley says he has attempted to coordinate with Feinstein's office to give Ford a chance "to be heard," but the request has so far been refused.

"Anyone who comes forward as Dr. Ford has deserves to be heard, so I will continue working on a way to hear her out in an appropriate, precedented and respectful manner," Grassley wrote in the statement.

"The standard procedure for updates to any nominee’s background investigation file is to conduct separate follow-up calls with relevant parties," Grassley added.

"In this case, that would entail phone calls with at least Judge Kavanaugh and Dr. Ford.

"Consistent with that practice, I asked Senator Feinstein’s office yesterday to join me in scheduling these follow-ups.

"Thus far, they have refused.

"But as a necessary step in evaluating these claims, I’ll continue working to set them up."

Grassley points out Feinstein's decision to withhold the allegations for six weeks while confirmation hearings and the vetting process took place.

"Unfortunately, committee Republicans have only known this person's identity from news reports for less than 24 hours and known about her allegations for less than a week," Grassley said in his statement.

"Senator Feinstein, on the other hand, has had this information for many weeks and deprived her colleagues of the information necessary to do our jobs.

"The Minority withheld even the anonymous allegations for six weeks, only to later decide that they were serious enough to investigate on the eve of the committee vote after the vetting process had been completed."